US President Donald Trump greets people negatively affected by the Affordable Care Act after calling on Republican Senators to move forward and vote on a healthcare bill to replace law in the Blue Room of the White House in Washington, US, July 24, 2017. [Photo/VCG]

WASHINGTON — A peeved President Donald Trump browbeat Republican opponents of his party's reeling health care bill Monday, asserting that his predecessor's signature overhaul has meant "death" and saying the Senate's planned faceoff vote is their chance to keep their pledge to repeal it.

Senate Majority Leader Mitch McConnell said he'd call a vote Tuesday on beginning debate on the legislation. While a victory on that initial but crucial roll call seemed an uphill climb, some Republicans expressed a new optimism that it would prevail — though the measure's ultimate fate still seemed gloomy.

McConnell, R-Ky., said he's "made a commitment to the people I represent" to undo President Barack Obama's health care overhaul, in what seemed a pointed reminder to Republican senators that they've made the same vow.

McConnell did not describe precisely what version of the GOP legislation senators would be voting on, though No. 2 House GOP leader John Cornyn of Texas said later that Republicans would discuss that at a private lunch before the vote. That omission has caused confusion and frustration among some Republican senators.

At the White House, Trump lambasted Democrats who helped enact the 2010 health care law and uniformly oppose the GOP attempt to scrap and rewrite it.

"They run out and say, 'Death, death, death,'" Trump said, with a backdrop of families that he said have encountered problems getting affordable, reliable medical coverage because of Obama's statute. "Well, Obamacare is death. That's the one that's death." Some Democrats have said the GOP repeal effort would lead to death for patients who lose coverage. The nonpartisan Congressional Budget Office has said various versions of the legislation would mean more than 20 million Americans would become uninsured by 2026.

But Trump focused many of his remarks on GOP senators. McConnell is nursing a slim 52-48 majority and the possible absence of Arizona Sen. John McCain, who's battling cancer, which would mean two GOP defections would sink the measure.

"For Senate Republicans, this is their chance to keep their promise. Over and over again, they said, 'Repeal and replace, repeal and replace.' But they can now keep their promise," Trump said.

At least a dozen Republican senators have publicly opposed or criticized the legislation, more than enough to kill it. That's forced McConnell to step back twice from anticipated votes and to revise his bill in hopes of mollifying unhappy moderates and conservatives.

Moderate Sen. Susan Collins, R-Maine, remained opposed to beginning debate on any option McConnell has revealed so far, and other Republicans remained uncommitted. But senators and aides said talks were underway on issues including potentially giving states more leeway on using federal funds to help people losing Medicaid coverage.